Just like how in the final stage, kiting is required, kiting is a must for Master, the inability to kite backwards due to monster re-spawning in a previously cleared room prevents kiting. there is only so much klting in a single room before you get cornered.
I can't even save explosive/acid/fire barrels to use to kite backwards. Everyone is already waiting for their mana and cooldown after clearing a room before proceeding to another room, I even wait for mana and cooldown if i run into monsters in the corridors leading to a new area.